This invention relates to a hook switch for telephone instruments having at least one set of contact springs placed inside a case.
In conventional hook switches the switching speed of the contacts depends on the speed of off-hook operation. A slow operation leads thus to a slow creeping contacting which has an ill effect on the working life of the contacts. Especially when d.c. is switched, a rapid switching speed is important to minimize burning off and creep of material. With rapid switching speeds, long periods of contact chattering which otherwise might occur can then be avoided.
Bounce switches that are fitted out with a bounce spring in the form of a C are well known. These consist of many single parts which must be individually coupled together in a casing with a C-formed spring and combined whereby an expended mounting is necessary. The contact pressure in both switching states can differ and vary when using a C-formed spring.
It is therefore an object of the invention to provide a telephone hook switch without the said disadvantages in switching behavior and consists of only a few parts which are assembled easily without additional connection elements. Thereby it is possible to have a simple structure, less expensive to assemble and which can be at least partly assembled by automation.
According to this invention, this is achieved by a bounce contact spring formed like a frame which has in its middle two spring blades which are arched outwardly in opposite directions and are connected at their lower end, with this lower end held in a bearing slot of an operation part which is connected to a switching balance.
According to this invention, there is further provided a slot in the operation part for its bearing on the bounce spring at the opposite side of the spring blades.
Another improvement is that in a hook switch with several bounce springs, the outer contact springs may be connected comb-like by a stamped strip that can be cut off after assembling with the operation part also formed comb-like and made of plastic.
A further feature is that the bounce contact springs and the outer contact springs are closely guided in chambers of the socket part.
According to the invention, there is further provided that the outer contact springs have an initial tension and lie against the interior wall of the socket part and have outwardly arched studs which set into corresponding cutouts of the socket part.
Another improvement is that the switching balance is fitted out with boreholes, that the socket part has pins that interlock into said boreholes and that the side walls of the switching balance are formed elastically.
A further improvement is that the switching balance has slots in which corresponding fingers of the operation part are interlocked when the switching balance is slipped onto the socket part.